One lucky James Maslow fan had her wish granted: to meet the handsome DWTS contestant.

Hannah Wackernagle, a 18-year-old Ohio high school senior with Down syndrome, invited her famous crush to her school prom – but because of scheduling conflicts, she received the ultimate surprise treat instead.

"It was the perfect week, because I knew she was [not only] a big Big Time Rush fan, but also a big Disney fan," Maslow, with Wackernagle at his side, told reporters backstage after scoring the first perfect 40 out of 40 for the season (more on that in a bit).

"So Peta [Murgatroyd] and I got together and got her tickets and we went on a bunch of rides and we got Mickey Mouse ears."

With a chuckle, the student, whose parents were also flown out for Monday's taping, admitted to PEOPLE that she was starstruck. Maslow said, however: "She's been really composed ... I think the only time I've gotten her to break down and laugh and giggle was when we started singing and dancing together."

Added the star: "This was a really unique opportunity for me. We get Tweets and mail every day saying, 'You help me, you make me smile, you've changed my life in a way' – but to be able to actually see it with someone and make their dream come true [is fulfilling]."

And while Maslow says, "Prom would have been cool," he felt like "this weekend was even cooler," adding: "I tried to make it as awesome as possible, and how often to get that opportunity? To me, it was really a blessing to have her and her family come out."

An added bonus? Performing the mind-blowing contemporary routine to the theme of Frozen that Wackernagle "liked a lot."

As for his show performance, Maslow said he was "really shocked" about the incredibly high marks, explaining, "It's been really nerve-racking because we were very ambitious. We had a dance in the first two days that was decent, but we wanted to step it up, so we threw in that last lift, which I guess has only been done once on the show, by Tony [Dovolani]. Tony showed us and said, 'Hey, go ahead, try it.' We were nervous, but we were very, very happy."